By now, it's firmly established that modern humans and their Neanderthal relatives met and mated as our ancestors expanded out of Africa, resulting in a substantial amount of Neanderthal DNA scattered throughout our genome. Less widely recognized is that some of the Neanderthal genomes we've seen have pieces of modern human DNA as well.
Not every modern human has the same set of Neanderthal DNA, however; different people will, by chance, have inherited different fragments. But there are also some areas, termed "Neanderthal deserts," where none of the Neanderthal DNA seems to have persisted. Notably, the largest Neanderthal desert is the entire X chromosome, raising questions about whether this reflects the evolutionary fitness of genes there or mating preferences.
Now, three researchers at the University of Pennsylvania, Alexander Platt, Daniel N. Harris, and Sarah Tishkoff, have done the converse analysis: examining the X chromosomes of the handful of completed Neanderthal genomes we have. It turns out there's also a strong bias toward modern human sequences there, as well, and the authors interpret that as selective mating, with Neanderthal males showing a strong preference for modern human females and their descendants.
Given how long modern humans and Neanderthals had been evolving as separate populations, some degree of genetic incompatibility is definitely possible. Lots of proteins interact in various ways, and the genes behind these interaction networks will evolve together—a change in one gene will often lead to compensatory changes in other genes in the network. Over time, those changes may mean re-introducing the original gene will actually disrupt the network, with a negative impact on fitness.
That means the introduction of some Neanderthal genes into the modern human genome (or vice versa) would be disruptive and make carriers of them less fit. So they'd be selected against and lost over the ensuing generations. Of course, some segments would likely be lost at random—the genome's pretty big, and the modern human population was likely large and growing, allowing its DNA to dilute out the influence of other human populations. Figuring out which influence is dominant can be challenging.
One way to sort this out is to make the same comparison with Neanderthal genomes. If a Neanderthal gene is disruptive in a modern human context, then it's likely that the modern human version will be disruptive in Neanderthals. And, in fact, that's what we seem to see: A look at one Neanderthal genome found that there's some correlation between the Neanderthal deserts in the human genome and the human deserts in that Neanderthal.
All of that, however, doesn't go far to explain the fact that the X chromosome looks like a giant Neanderthal desert, with long stretches of nothing but modern human DNA. The genetics of the X is complicated by the fact that males inherit a single copy from their mothers, so they have only a single copy of almost every gene on it. If any of those genes are causing problems, they will be quickly selected against in males.
Thus, evolutionary selection against the Neanderthal X is definitely an option. The alternative they consider is that it's the product of biased matings. If most mating between the two groups was biased in some way, it could skew the frequency with which the X chromosome was inherited. For example, if most of the matings involved Neanderthal males and modern human females, then you would have fewer Neanderthal X's around as a result, since only half of a male's offspring will inherit an X chromosome from them.
To figure out which result might be the case, the researchers again turned to the three Neanderthal genomes we have available, looking at the pattern of inheritance along the X chromosome. That was compared to X chromosomes from African populations that have very little Neanderthal DNA.
The results contrasted sharply with what was seen elsewhere in the genome, where Neanderthal deserts in modern humans correspond to human deserts in the Neanderthal genome. Instead, the X chromosome in Neanderthals tended to have an excess of modern human sequences—exactly as you see in modern humans. It appears that the modern human X ended up more common in both human and Neanderthal populations.
Could this be from evolutionary selection for something favorable about it? The researchers found that modern human DNA found on the Neanderthal X had a lower than average frequency of important sequences like those that regulate nearby genes or code for proteins. While that doesn't rule out evolutionary selection as a factor, it does make it seem a bit less likely, since there's less indication that the DNA being kept around is functional.
That leaves preferential mating as a more probable explanation. But the modern human DNA was present at such a high frequency on the X that it's difficult to explain by a simple preference of Neanderthal males for modern human females. Instead, you'd have to have a continued preference for the offspring of these matches as well. "We did not rule out more complicated scenarios combining selection and sex biases, such as natural selection acting as a modifying force on top of the strong signature left by sex bias," the authors also note.
Overall, we're left with a picture of a relatively large number of matings between male Neanderthals and modern human females. The offspring of these matings ended up in both the modern human and Neanderthal populations; in the latter, their offspring were favored enough to have led to an excess contribution to the X chromosome.
Science, 2026. "Interbreeding between Neanderthals and modern humans was strongly sex biased"
DOI: 10.1126/science.aea6774 (Source).
(Score: 5, Insightful) by looorg on Sunday March 01, @08:27PM (2 children)
Why can't it have been the other way around? Homo Sapiens Women having a thing for Homo Neanderthalensis men? They liked them big and stupid.
It can't all be caveman Grog bonking some human female over the head and dragging her back to his cave for some less then consensual snu-snu.
(Score: 2) by JoeMerchant on Sunday March 01, @09:25PM
In some areas, maybe.
The story is really told in the relative size and strength tendencies of XY and XX chromosomal configurations. In the Amazon, they did evolve XX bigger and stronger - it was the women bonking the men over the head and dragging them back to their hammock. In most of the rest of the world...
🌻🌻🌻🌻 [google.com]
(Score: 2) by krishnoid on Tuesday March 03, @02:46AM
I bet it goes both [youtu.be] ways [youtu.be] [note, offensive clip from Sascha Baron Cohen movie].
(Score: 3, Funny) by Anonymous Coward on Sunday March 01, @08:29PM (2 children)
In high school, all the cute gals were picked up by the Neanderthals (aka football players).
As it turned out, this probably wasn't the best strategy, since the nerds now rule and the Neanderthals lost (except for a very few that were good enough for professional sports).
(Score: 1, Funny) by Anonymous Coward on Sunday March 01, @09:26PM
The Neanderthals want to make the Late Pleistocene great again.
(Score: 2) by driverless on Monday March 02, @11:29AM
Came here to point out the same thing, the story is about cavemen, not tech bros.
(Score: 2, Interesting) by shrewdsheep on Sunday March 01, @08:52PM (2 children)
What has been well documented in Humans is that when one people invaded the land of another, males got killed and women got raped (e.g. the Americas). I could imagine that in the few instances that H. neanderthalensis could overcome H. sapiens, they would have done the same. Unspeakable aggression is one of our difficult heritages and we see examples thereof to this day.
(Score: 1, Funny) by Anonymous Coward on Sunday March 01, @09:28PM
Those primitive savages were Saved(tm) by the loving bosom of Christian fundamentalists.
Psalm 137:9 "Happy is the one who seizes your infants and dashes them against the rocks"
(Score: 3, Interesting) by aafcac on Monday March 02, @05:02AM
That happened, but you also had women that went for the folks in charge either because they wanted the security or that was what was available. It was hardly just rape going on there. And while that whole "legitimate rape" line is nonsense, there's a bunch of stuff that happens during consensual sex that does somewhat boost the likelihood of any kids coming of it. It's not like women evolved to reward that sort of thing any more than couldn't be avoided. If it had, we'd likely see very different attitudes towards it globally rather than just in pockets where it's dying out.
(Score: 2) by VLM on Sunday March 01, @09:02PM (8 children)
The older view, like pre-baby boomer era, was Neanderthals' were really, really dumb compared to the humans, like Neanderthals were living in caves while the humans were building UFOs in Atlantis. Boomer era and more modern outlook is they were about the same level of intelligence.
From what I remember the brain structure differences were pretty minimal and the Neanderthals likely had minimally higher visuospatial IQ component scores and the humans likely had minimally higher abstract reasoning scores but the aggregate IQ score would roughly be about the same. When it came to a hunt Neanderthals might have been slightly better at mental maps and Humans might have been slightly better at planning hunts or something, but it would be a pretty small difference.
In a way this makes sense. They couldn't manage to wipe each other out in just a couple years it seemed to take a VERY long time; intuitively that would imply they're a really close match if it took half of forever for one side to win. Probably closer match than you get between modern human races as they didn't have international air travel etc.
The Neanderthals were bigger and had more muscles and its pretty rare for female animals, mammals, or primates to select for scrawny and starving looking, so ... Its a dual edged sword in that bigger muscle needs more food; take down more and larger wooly mammoths which is awesome when more are around, but fueling those muscles kinda sucks during a famine.
I'd bet the babes swarmed the Neanderthals during the good times, but no matter how often the human males got friendzoned, if the Neanderthals starved to death during famines they were just F-d in the long run. This would seem to indicate famines were a pretty big problem back in the day.
The modern propaganda outlook of weak sickly people are smarter is ... very modern, and also totally false. Virtually all studies I've found indicate strength/health correlates very positively with IQ. Which makes sense if both are influenced on the positive side with lots of food and both are influenced on the negative side by genetic diseases and diseases in general. Physiognomy, it seems, is real after all, at least according to statisticians and medical peeps. Its always the philosophers, politicians, and weak/ugly people who get all butthurt about it, which is pretty funny. Kind of like "healthy at every size" movement but for ugliness instead of fat percentage.
Some of the statistical analyses are wild, like hand grip strength correlates strongly and positively with IQ.
My life long association with other gym rats is gym rats have more self discipline and self control in their pinky toe than the average lazy couch potatoe has in their entire body, and that successful self discipline is likely an expression of higher intelligence.
(Score: 2) by HiThere on Sunday March 01, @09:28PM (1 child)
IIUC, the Neanderthals were probably about as intelligent as Cro-Magnon on an individual level, but they tended to live in much smaller groups, and so didn't get as much cultural reinforcement. It takes a certain population size to hold onto, much less advance, a technology.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 3, Informative) by aafcac on Monday March 02, @05:05AM
That's more or less my understanding. A good chunk of why we're here and they aren't is that we developed sex roles that cut out a lot of wasted energy that could be used for reproduction. These days, the sex roles are mostly optional as we've got tools and machines that allow even small people to do things that would have been challenging to large, strong workers a hundred years ago. But, back then, it was a pretty significant advantage in being able to have women that didn't need the same level of upper body strength and could specialize in things like reproduction and cooking that don't require nearly as much upper body strength.
(Score: 4, Insightful) by JoeMerchant on Sunday March 01, @09:31PM (1 child)
> Humans might have been slightly better at planning hunts or something, but it would be a pretty small difference.
That small difference is how wars are won and lost.
The US didn't end up on the winning side of WWI and WWII through superior firepower or numbers of troops, the US primarily had the advantage of its protected rear area, time spent planning supply lines / logistics. Effective organizational hiearchy is how you field an army with a purpose, rather than a bunch of individual heroes suiciding themselves trying to take machine gun nests.
To sum up: you are saying Neandertals made the better individual hunter, but h. sapiens had better group cohesiveness. Even if it's just a marginal difference, that has been decisive throughout history.
🌻🌻🌻🌻 [google.com]
(Score: 1, Interesting) by Anonymous Coward on Monday March 02, @01:20AM
> ... the US primarily had the advantage ...
... of true mass production. The giant integrated Volkswagen plant that Hitler funded was based on what Henry Ford had already done roughly 20 years before with his vertically integrated Rouge Plant. While the VW staff managed to convert to making something for their military, it was not high production. Basically none of the Axis war production factories came close to matching the quality and quantity of the arsenal of democracy https://en.wikipedia.org/wiki/Arsenal_of_Democracy [wikipedia.org]
(Score: 0) by Anonymous Coward on Monday March 02, @12:34AM (1 child)
> They couldn't manage to wipe each other out in just a couple years it seemed to take a VERY long time; intuitively that would imply they're a really close match if it took half of forever for one side to win.
I think they were all just trying to stay alive. Back then there were plenty of nasty predators around. You make it sound like moderns and Neanderthals were the only enemies, but the population density was so low that much of the time they may not have even come across each other.
(Score: 2) by aafcac on Monday March 02, @10:53PM
Or they weren't trying to wipe each other out and were more focused on the practical considerations of things like food, safety and shelter.
(Score: 0) by Anonymous Coward on Monday March 02, @01:41AM
And that IMO is how humans evolved to run long distances. When the predator and prey are similar species...
It ain't the persistence hunting as popularly known. Normal people wouldn't normally run that long just to get lunch, they'd use their brains to outsmart their lunch. BUT when the brains and running speeds are similar...
You can't wipe them out if enough of them run away.
(Score: 1, Funny) by Anonymous Coward on Monday March 02, @05:15PM
couch potatoe
Dan Quayle, is that you? I claim my $5.
(Score: 0, Touché) by Anonymous Coward on Monday March 02, @09:39AM
Orange Man and his mouthpiece "Goebbels Barbies"
(Score: 2) by cosurgi on Monday March 02, @02:34PM
So Neanderthals invented time travel to meet with modern females :)
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